This is the main module to be included by code using the Labeled IO
(LIO) library. This module exports the core library (documented in
LIO.Core), with support for labels and privileges (documented in
LIO.Label) and labeled values (documented in LIO.Labeled).

Certain symbols in the LIO library, particularly those in
LIO.Exception, use the same names as their IO equivalents in the
system libraries. Hence main modules consisting mostly of IO code
that simply need to run LIO code should import LIO.Run (or
LIO.DCLabel) to avoid polluting their namespaces.

Most code will need to use a particular label format, which needs to
be imported separately. Hence, a typical set of imports for an
untrusted LIO module is: